mPEG-CHO

mPEG-CHO is a type of methoxy polyethylene glycol aldehyde (mPEG-CHO) derivative used in bioconjugation, particularly for site-specific pegylation of proteins, peptides, and other biomolecules. This compound features an aldehyde functional group (-CHO) attached to the end of a polyethylene glycol (PEG) chain, which allows for selective conjugation to primary amines, usually through a Schiff base formation followed by reduction to form a stable secondary amine linkage.

Key Characteristics

• PEG Chain: The PEG component (mPEG) provides increased solubility, reduced immunogenicity, and enhanced stability to the conjugated molecule.
• Aldehyde Group: The aldehyde group specifically reacts with amino groups, particularly on lysine residues or the N-terminal amine of proteins and peptides.
• Molecular Weight: Available in various molecular weights, typically ranging from 2,000 to 20,000 Da, influencing the solubility, hydrodynamic radius, and in vivo half-life of the conjugates.

Applications

• Site-Specific Pegylation: mPEG-CHO enables targeted modification of biomolecules, improving pharmacokinetics and reducing immunogenicity without significantly altering the biological activity.
• Drug Delivery: The PEGylation of therapeutic proteins or peptides helps in extending the circulation time and enhancing the efficacy of drugs.
• Bioconjugation: Used in forming PEG-protein conjugates for therapeutic and diagnostic purposes, facilitating controlled delivery and reducing the potential for immune responses.

Conjugation Mechanism

• Reaction Initiation: The aldehyde group reacts with the primary amine on the target molecule, forming an imine (Schiff base).
• Reduction Step: The imine is usually reduced by a reducing agent (like sodium cyanoborohydride), resulting in a stable secondary amine linkage.

Considerations

• pH Sensitivity: The reaction is pH-sensitive, typically optimized around neutral pH (pH 6.5–7.5).
• Reduction Requirement: To stabilize the Schiff base, a reduction step is necessary, otherwise, the linkage remains reversible.

mPEG-CHO AffiPEG is primarily utilized in the pharmaceutical and biotech industries for the modification of therapeutic agents to improve their delivery and efficacy profiles.